java - 在java中随机选择的对象上调用通用方法的更好方法

Question

祝大家今天愉快。

我有一个带有方法 runRandomExercise() 的抽象类，以及几个扩展它以添加不同类型练习的类。

我现在想选择一个随机类型的练习，所以我需要随机选择一个类，然后调用 runRandomExercise()。

目前我正在手动编码，这不是我认为的最佳解决方案。但是，我不能只将类存储在数组中，因为类类型不同，而且如果我使用 object[]，我就不能调用 runRandomExercise() 方法。有什么聪明的方法来处理这个问题吗？

到目前为止，这是我的代码。它可以工作，但是添加其他类会很痛苦...

/*Specific classes that extend abstract class TrainingClass with the runRandomExercise() method*/
private MatheMagic mMathMag;
private Mnemonics mMnemonics;
private String[] mTrainingClasses;


/*Initialize classes*/
mMathMag = new MatheMagic();
mMnemonics = new Mnemonics();

/*Manually store classe names*/
mTrainingClasses = new String[2];
mTrainingClasses[0] = "mMathMag";
mTrainingClasses[1] = "mMnemonics"; 


/*Return random exercise*/
public String[] RandomExercise() {
    Random aGenerator = new Random();

    /*Get random class name*/
    int rnd = aGenerator.nextInt(mTrainingClasses.length);
    String aChosen = mTrainingClasses[rnd];

    String[] aRes = new String[2];


    if (aChosen == "mMathMag") {
        aRes = mMathMag.runRandomExercise();
    } else if (aChosen == "mMnemonics") {
        aRes = mMnemonics.runRandomExercise();
    }

    return aRes;
}

编辑以下是 TrainingClass 的定义方式:

/** Common interface for all exercises */ 
public interface Exercise { 
   public String[] run();
}

/** Common interface for all training classes */
 public abstract class TrainingClass {

  private Random mRandGen = new Random();
  public ArrayList<Exercise> mExerciseTypes = new ArrayList<Exercise>();

  /** Run a random exercise */
 public String[] runRandomExercise() {
    int i = mRandGen.nextInt(mExerciseTypes.size());
    return mExerciseTypes.get(i).run();
 }
}



/*Specific training class*/

public class MatheMagic extends TrainingClass {

 public MatheMagic() {

    class SomeExercise implements Exercise {

        public String[] run() {

             String[] mRes = new String[2];
              mRes[0] = "Question type 1";
              mRes[1] = "Answer type 1";
            return mRes;
        }

    }

    class SomeOtherExercise implements Exercise {

        public String[] run() {

             String[] mRes = new String[2];
              mRes[0] = "Question type 2";
              mRes[1] = "Answer type 2";
            return mRes;
        }

    }
    SomeExercise mN = new SomeExercise();

    SomeOtherExercise mS = new SomeOtherExercise();

    mExerciseTypes.add(mN);
    mExerciseTypes.add(mS);
 } 

}

Answer 1

简单的解决方案是使用通用方法创建一个接口(interface)，并让您的所有类扩展它。

创建该类型的集合或数组而不是对象；您可以简单地遍历或随机选择并调用您想要的方法。

给我的感觉就像是 GoF 的命令模式。

public interface Exercise {
    void execute();
}

现在你的类这样做:

public class MatheMagic implements Execise {
    public void execute() {
        // special logic here.
    }
}

然后你可以这样做:

int numExercises = 1;
Exercise [] exercises = new Exercise[numExercises];
exercises[0] = new MatheMagic();
for (Exercise exercise : exercises) {
    exercise.execute();
}